What part of plant lighting am I mis-understanding?

  • We are currently upgrading MFK. thanks! -neo
BadOleRoss;4003090; said:
Granted, I am still trying to educate myself on this lighting mess, but wouldn't going by lumens and the kelvin rating satisfy both the unit of brightness and the photosynthetic activity?
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what you actually want to look at is PAR(photosynthetically active radiation), even at with the proper kelvin bulb there still is some unusable light, so lumens are flawed also.
 
FYI.... I got 3x t8 x 48" on my 75g tank. Currently using philip's 6500k/ 2800 Lm per bulb. Got them in a 10 pack for pretty cheap from home depot.
 
BadOleRoss;4006776; said:
Yes, it was on the dry side but it did have a lot of useful info. I now believe I can use the 6500 lamps but will have to supplement them with 14000s or higher because of the water depth.
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depth has nothing to do with what kelvin rating you should/ want to be using and that's because a 14000k lamp is producing just as much light as a 6500k lamp just more of it is blue which actualy looks not as bright as red or green
 
Zander_The_RBP;4009061; said:
depth has nothing to do with what kelvin rating you should/ want to be using and that's because a 14000k lamp is producing just as much light as a 6500k lamp just more of it is blue which actualy looks not as bright as red or green
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According to this, it does affect the PAR. My current hood has enough room for 16 4' bulbs. Right now I have 4 bulbs on hand. When I get the other 12 bulbs it seems like a nice mix might be the way to go. Maybe 10 6500s and 6 14000s. Keep in mind, I am still learing all this lighting stuff, if I am getting bad info someplace, dont hesitate to point it out.


Light Penetration

As well for tanks over 24 inches the use of some higher Kelvin in your light “mix” may be necessary for coral tanks or in some cases high light requiring plant tanks. The use of 14,000 K MH in a mix with High PAR 6400 K SHO lights may provide the “mix” necessary for deeper tanks. Even in tanks under 24 inches, the use of actinic blue lights may help provide the correct PAR to specimens lower in your tanks water column; a LED light strip may help provide this.
 
jschall;4001467; said:
Lumens measure visible light, and are weighted based on the sensitivity to the human eye (which peaks in the greens.)
Photosynthesis occurs from light in the deep red and deep blue ranges, of which the human eye sees very little. Greens don't help much, if at all.

Everyone has different bulbs, outputting different spectrums at different efficiencies with different quality reflectors. I truly don't believe you can quantify it in watts per gallon or lumens per gallon or anything else per gallon.

Maybe if manufacturers started rating their bulbs based on a unit of brightness which is weighted for photosynthetic activity, there would be a proper way to select a lightbulb.
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I agree. It's all bout coloration af the bulbs. High "wattage", hell yeah. Spectrums is where is at.
 
Zander_The_RBP;4009061; said:
depth has nothing to do with what kelvin rating you should/ want to be using and that's because a 14000k lamp is producing just as much light as a 6500k lamp just more of it is blue which actualy looks not as bright as red or green
Click to expand...

the kelvin rating does effect the lumen and par output of the light. However it should barely make a difference for your purposes(assuming you don't get a extremely high kelvin with very little par).

also It is true blue light does go through water better, but unless your depth is measured in 10's of feet it won't really matter.
 
BadOleRoss;4009670; said:
According to this, it does affect the PAR. My current hood has enough room for 16 4' bulbs. Right now I have 4 bulbs on hand. When I get the other 12 bulbs it seems like a nice mix might be the way to go. Maybe 10 6500s and 6 14000s. Keep in mind, I am still learing all this lighting stuff, if I am getting bad info someplace, dont hesitate to point it out.


Light Penetration

As well for tanks over 24 inches the use of some higher Kelvin in your light “mix” may be necessary for coral tanks or in some cases high light requiring plant tanks. The use of 14,000 K MH in a mix with High PAR 6400 K SHO lights may provide the “mix” necessary for deeper tanks. Even in tanks under 24 inches, the use of actinic blue lights may help provide the correct PAR to specimens lower in your tanks water column; a LED light strip may help provide this.
Click to expand...
i think that may be bad Info(but i could be wrong) i see no actual science behind it. Blue light penetrates further into water than red light and green light so using a higher rating kelvin bulb on a VERY deep tank makes sense (plants use blues or reds so suppling light that penetrates further(blues) is a good idea on a deep tank) But that realisticaly is only going to happen in tanks deeper than 4 feet


mgk;4010566; said:
the kelvin rating does effect the lumen and par output of the light. However it should barely make a difference for your purposes(assuming you don't get a extremely high kelvin with very little par).

also It is true blue light does go through water better, but unless your depth is measured in 10's of feet it won't really matter.
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i should have worded what i was saying better it's still producing the same amount of radiation but less of it you can actualy see (more UV) and the light it produces is bluer which appears not as bright as greens
 
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